The present invention relates to improvements to a high-pressure pump for feeding fuel to an internal combustion engine, in particular a vehicle engine.
High-pressure pumps of the above type normally comprise a body housing at least one cylinder in which a piston slides; and a head having a surface engaging a corresponding surface of the body to fix the cylinder. The head also has an intake conduit, the inlet of which is located at the head surface next to the cylinder seat.
In one known radial-cylinder pump, each cylinder is fixed by a corresponding head; a single seal of elastomeric material is inserted between the surface of each head and the body surface, and comprises an arc-shaped portion of a given diameter, which fits about the cylinder, and a smaller-diameter arc-shaped portion, which fits about the intake conduit inlet; and the section of the seal is normally elongated in a direction parallel to the head surface.
A major drawback of the above known pump lies in the seal stretching when subjected to high temperature. At pump temperatures of over 140xc2x0 C., in particular, the seal tends to close at the connecting regions of the two arc-shaped portions, thus possibly choking or closing the inlet of the intake conduit. Moreover, since the choking effect differs from one cylinder to another, both activation and delivery of the pump are unbalanced, thus resulting in possible damage to the pump and in irregular supply to the engine.
It is an object of the present invention to provide straightforward, reliable improvements to the seals of a high-pressure pump, to eliminate the aforementioned drawbacks typically associated with known pumps.
According to the present invention, there is provided a high-pressure pump for feeding fuel to an internal combustion engine, and which comprises a body housing at least one cylinder in which a piston slides, and a head having a mating surface facing a corresponding mating surface on said body to fix said cylinder; said head having an intake conduit and a delivery conduit; said intake conduit having an inlet located at the mating surface of said head; and said body having a feed conduit having an outlet located at the mating surface of said body and at said inlet; characterized in that, between said mating surfaces, a first seal is placed about said cylinder, and a second seal about said inlet; said seals being separate and made of elastomeric material.